Last Seen on Nantucket

When thirty-two-year-old Katie Chapman vanishes during an early morning run, Nantucket detectives Tina Fisch and Rick Caton suspect a shocking but isolated abduction on an island that prides itself on safety and discretion.

It isn't isolated. It isn't random. She was chosen.

For Rick, the case is personal. After solving the suspicious death of a close family friend the previous fall, he left the FBI and returned to Nantucket—and to the police department that forced him out a decade earlier.

As...